JPS605826B2 - 4-way switching valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When a single pump selectively supplies pressure oil to multiple circuits, a plurality of switching valves are connected and used, and the present invention relates to an improvement of the switching valve described above.

When connecting multiple switching valves as described above,
Conventionally, tandem center type or closed center type switching valves have been used, and FIGS. 1 and 2 show specific examples of such switching valves actually used by the present applicant. In the system shown in Fig. 1, which connects two tandem center type lightning switching valves 1 and 2, all the load pressure of the downstream circuit connected to the switching valve 2 is transferred to the tank boat side of the switching valve 1. Acts as back pressure.

However, in this type of switching valve, the sliding portion of the spool is partitioned by a seal member to partition the solenoid portion and the valve portion. When the load pressure on the downstream side acts as back pressure on the tank boat side on the upstream side, the load pressure also acts on the seal member, so a high-pressure seal with large friction must be used as the seal member. . For this reason, conventional switching valves have the disadvantage that the sliding properties of the spool deteriorate due to the influence of friction in the seal portion, and the responsiveness thereof also deteriorates.

In addition, tandem center type sliding valves often use a hollow spool that forms the neutral oil passage within the spool.
In this case, it is difficult to make the neutral oil passage large due to the valve structure.

If this neutral oil path is to be made larger, the diameter of the spool must be made larger. Therefore, if the spool diameter is increased, the other parts must also be made larger, so if there are restrictions on the size of the equipment, the neutral oil path cannot be made large, and therefore it is necessary to have sufficient flow rate in the downstream circuit. There was also the drawback that it was not possible to supply

On the other hand, in the case shown in Fig. 2 in which two closed center type electromagnetic switching valves 3 and 4 are connected, the load pressure of the downstream circuit is equal to Although it does not act as back pressure on the switching valve or restrict the flow rate, the unload valve 6 is used to prevent the relief valve 5 from operating when both switching valves 3 and 4 are held at the center position. This had the disadvantage of increasing costs.

In this invention, when the spool is held in a neutral position,
The four-way switching system prevents the downstream load pressure from acting as back pressure on the tank boat side of the upstream switching valve, and also allows sufficient flow to be supplied to the downstream actuator in this state. The purpose is to provide valves.

The illustrated embodiment will be described below. In this embodiment, the same type of electromagnetic switching valves X and Y are connected in series, and the specific configuration will be explained only for one electromagnetic switching valve x. do.

In the electromagnetic switching valve x, a spool 8 is housed inside a valve body 7, and rod portions 8a and 8b at both ends of the spool 8 penetrate through spring receivers 22 and 23 and protrude toward the solenoid 9 side.

The rod portions 8a and 8b have seal members 24,
25 is provided to partition the solenoid 9 side and the valve portion. Then, the rod portions 8a and 8b are pushed by the solenoid 9, and the spool 8 is slid from side to side to move the pump boat P, actuator ports A, B, and tank boat T, respectively. or block traffic.

Further, the valve body 7 is provided with an outflow boat N that passes through the pump boat of the other electromagnetic switching valve Y, and a passage 10 and a pot 11 are provided between the pump boat P and the outflow boat N, so that the spool 8 is in the neutral state. Only when held in position does the povet 11 open, allowing both boats P and N to pass through.

Raiji switching valve Each switching mechanism is exactly the same as a conventional electromagnetic switching valve. However, an outflow boat N suitable for the pump boat of the other electromagnetic valve Y is provided in the valve body 7, and a passage 10 and a bobbet 11 are provided between the pump boat P and the outflow boat N, so that the spool 8 is maintained in a neutral position. This is different from the conventional method in that the pot 11 opens only when the boat is opened, allowing both boats P and N to pass through.

The pressure fluid flowing from the pump boat P flows into the pressure chamber 13 through an orifice 12 formed in the pot 11.

This pressure chamber 13 communicates with an annular groove 15 via an oil passage hole 14, but this annular groove 15 may or may not pass through the tank boat T depending on the position of the spool 8. That is, as is clear from FIG. 4, the spool 8 has a horizontal hole 17 that passes through the outermost land 16 and is suitable for the tank boat T, and a vertical hole 18 that crosses and communicates with this horizontal hole 17.
is formed, and the vertical hole 18 is set in a relationship that fits the annular groove 15 only when the spool 8 is maintained in the neutral position, and therefore the spool 8 is maintained in the neutral position. In some cases, the pressure chamber 13 is suitable for a tank boat T. Now, for example, in order to use the upstream circuit, the spool 8 of the electromagnetic switching valve
Alternatively, if the pressure chamber 13 is set to the out position, the communication between the pressure chamber 13 and the tank boat T is cut off, so the pressure fluid flowing into the pressure chamber 13 acts on the pot 11 as described above, and the spring Combined with 19, the said Bobet 1
Seats 1 and 2 are placed in close contact with each other to block communication between the pump boat P and the outflow boat N.

In other words, no pressure fluid is connected to the downstream circuit. Next, when the spool 8 is set to the neutral position, the pressure chamber 1
3 becomes tank pressure, the pot 11 is pushed open against the spring 19, and the pressure fluid from the pump boat P flows out from the outflow boat N to the pump boat of the other electromagnetic switching valve Y. When the spool 8 is held in the neutral position as described above, the pressure fluid from the pump boat P does not flow into the tank boat T side, but flows from the outflow boat N into the electromagnetic switching valve Y on the downstream side. Even if the actuator on the downstream side is operated, the load pressure of the actuator does not act on the tank boat T side.

In other words, the load pressure on the downstream side
, 25, the seal members 24, 25 can be used as low pressure seals. Since a low-pressure seal can be used in this way, the sliding properties of the spool 8 are not impaired. In addition, as is clear from Fig. 5, the outflow boat of the downstream electromagnetic switching valve Y is located in the tank 2.
I'm letting Ren go through 1.

As is clear from the above description, the configuration of the present invention is such that a pump boat, an actuator boat, and a tank boat are provided in the valve body, and the flow path switching operation is performed by sliding an internal subur on the valve body. In a four-way switching valve in which both ends of the spool are sealed with sealing members, an outflow boat provided in the valve body and the pump boat are connected to each other via a bobbet, while the outflow boat from the pump boat is connected to the bobbet. An orifice is formed to introduce pressure fluid into the pressure chamber, and depending on the pressure balance between this pressure chamber and the pump boat, the povet opens and closes to allow the pump boat and outflow boat to communicate or to block the communication. In addition, only when the spool located between the pressure chamber and the tank boat is in a neutral position, the pressure chamber and the tank boat are allowed to communicate through the spool, and the povet is opened. Has characteristics.

Under this configuration, when the spool is in the neutral position,
Pressure fluid flowing in from the pump boat forces the povet open and flows out from the outflow boat.

In other words, since the pressure fluid does not flow into the tank boat side, the load pressure of the actuator on the downstream side does not act on the sealing member provided on the spool. In this way, since the load pressure of the actuator on the downstream side does not act on the seal member, the seal member can be used as a low-pressure seal.
Accordingly, the spool's durability can be maintained better.
In addition, since the pressure fluid from the pump boat pushes open the povet and flows out from the outflow boat, for example, the flow path can be made larger than when a neutral flow path is formed in the spool, and the supply flow rate can be increased accordingly. can be secured.

Furthermore, the neutral position of the spool is used to supply pressure fluid from the pump to the downstream switching valve, so as long as each of these switching valves is in the neutral position, the pressure fluid from the pump will continue to flow. Return to tank.

Therefore, there is no need to provide a special unload valve as in the conventional case, and the cost can be reduced accordingly.

[Brief explanation of drawings]

Figures 1 and 2 are circuit diagrams in which conventional electromagnetic switching valves are connected in multiple ways, Figures 3 to 5 show one embodiment of the present invention, and Figure 3 shows one of the two electromagnetic switching valves. FIG. 4 is a cross-sectional view taken along the line X-X in FIG. 3, and FIG. 5 is a circuit diagram. 7... Valve body, P... Pump boat,
A, B... Actuator port, T... Tank boat, 8. ．． ．． 、．・Spool, N...Outflow boat, 11...-Pobet, 13...Pressure chamber,
12... Orifice. Ku diagram Oh no diagram talent 3 diagram power 4 figure diagram

Claims (1)

[Claims] 1 A pump port, an actuator port, and a tank port are provided in the valve body, and the flow path is switched by sliding an internal spool on the valve body, and both ends of the spool are sealed with a sealing member. In the four-way switching valve, an outflow port provided in the valve body and the pump port communicate with each other via a poppet, and an orifice is formed in the poppet to introduce pressure fluid from the pump port into the pressure chamber. Depending on the pressure balance between the pressure chamber and the pump port, the poppet opens and closes to connect or disconnect the pump port and outflow port, and the spool located between the pressure chamber and the tank port opens and closes. A four-way switching valve configured to allow communication between a pressure chamber and a tank port via the spool and to open the poppet only when the poppet is in a neutral position.